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Christina Rinas of APU

As earth's climate warms plant communities are changing. In particular, scientists have seen an increase in shrub biomass, abundance, and distribution in Arctic and alpine tundra, collectively termed “shrub expansion”. While studies indicate that climate change underlines this growth, local influences may account for some of the variability across the landscape. (click on photo for more of the story)

For more than two years, Christina Rinas has been investigating the impact of these local influences on shrub expansion in the Western Chugach Mountains. Rinas, an environmental science student at the Alaska Pacific University, discussed her findings during her thesis defense in April.

As part of her research, Rinas analyzed historic and current aerial imagery in the Western Chugach Mountains, on lands managed by the Joint Base Elmendorf-Richardson. She studied how alder and willow changed in distribution and abundance in the subalpine-alpine ecotone, gathering data from a forty-year period between 1972 and 2012.

“My research provides a baseline for future studies, and will help land managers and the local community understand how vegetation in our area is changing,” Rinas said. While shrub expansion has been documented throughout the circumpolar north in Arctic and alpine areas, little is known about how shrubs are changing in the Western Chugach Mountains. An increase in shrubs may alter ecosystem processes, biodiversity, wildlife habitat, and recreational activities in the Chugach Mountains.

The Western Chugach is home a vast array of wildlife. Large animals like bears, wolves, moose, and wolverines call the area home. According to Rinas, shrub expansion may alter wildlife habitat at higher elevations. Some animals reliant on open areas – like arctic ground squirrels and pikas – may be losing habitat due to shrub expansion.

During her study, Rinas discovered that both alder and willow are increasing in cover and altitudinal distribution in the Western Chugach. She observed that willow patches were expanding onto herbaceous meadows and low shrub communities in areas with higher solar radiation, often times next to alder patches that had not changed noticeably across the decades. In contrast, alders were more likely to expand onto dwarf shrub tundra in areas with lower solar radiation.

Recounting the project, Rinas said that the best part was working with numerous talented scientists and students. “I've learned so much,” she said.